What is CORS?
In short
- CORS, short for cross-origin resource sharing, is the browser rule that decides when code on one domain may read data from another.
- When it blocks a request, the console shows an error and the data never loads.
- It usually appears when a hosted app calls an external API that has not allowed your origin.
CORS is a safety rule built into every browser. JavaScript running on one domain cannot read a response from a different domain unless that server allows it with the right header. The rule stops a random page from reading your email or your bank account in another tab. The side effect is that an innocent app can hit a wall when it fetches data from an API that has not opted in.
People meet this error most often after they deploy a React app, because an app built with an AI tool usually calls an external API. The page loads, then a fetch to another service fails with a cross-origin message in the console. The fix belongs on the API side, where the service has to send a header naming your origin as allowed. NudgeHost serves your files with correct headers so they load cleanly, but it cannot grant permission on an API it does not control.
A page built only from inline code and CDN scripts never runs into CORS, because it makes no cross-origin data requests. That covers most single-file pages, such as the ones people publish straight from ChatGPT. The rule surfaces only when your code talks to a separate backend. Hosting is free to start, and a Pro subscription raises the file-size limit for bigger builds. If a hosted app cannot reach an API, check whether that API allows your origin before blaming the host.
Related terms
Frequently asked questions
Why does my hosted app get a CORS error?
Your code is calling an API on another domain that has not listed your origin as allowed. The API has to send the right header, and a host cannot add it for a service it does not own.
Does CORS affect a plain HTML page?
Only if the page makes cross-origin data requests. A self-contained page using inline code or CDN scripts never triggers it.
Can NudgeHost fix a CORS error for me?
NudgeHost already serves your files with correct headers. The blocked request runs between your code and a third-party API, so you or the API provider have to configure it.
Related tools
Other things you can do on NudgeHost.
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